I know many people will disagree with me, but Stover is a wordsmith. Drew always has exciting endings and Zahn really makes you think. Luceno used to be good, but his last 2 novels sucked.
Luceno, Stover and Sean Stewart (only had one entry, but it was great).
Revan is probably irredeemable. Drew's lack of research before writing his books is noticeable when he has Sirak using Vaapad and the Triumvirate slaughtering tens of thousands of Jedi. Or Meetra being unable to cope with the prospect of not feeling the Force. With only a few exceptions, his characters are as a devoid of characterization as Nathema is of life.
Better to have lost it than to have never had it tbh.
I'm not nearly as well-versed on the EU as anyone here, but I couldn't get much further than the first page of Revan. From a purely technical perspective Drew is horrible, lol, and what little I've read of his Mass Effect novels seem to confirm that. His prose is unusually bad for a professional author.
By contrast, I'm reading through Darth Plagueis right now and Luceno is at least technically competent.
Stover is by far the best writer in the star wars verse that has had More than one entry.
Luceno is arguably a contender for top dog but his books are of an acquired taste, while Stover manages to draw both audiences with his grasp of character and story telling ability.
Timothy Zahn isn't someone I can judge because I've never read his stuff in it's entirety. But one author I do think has considerable talent is Paul S Kemp(author of Crosscurrent/Riptide in Legends Canon and Lords of the Sith in Disney Canon)
Kemp brings a lot to the table, great story telling, a lot of focus on character development and he actually does research on characters(He went through various sources for Jaden Korr, played the game and even went to Wookieepedia to boot)